Melamine cause of contaminated pet food

Melamine, a chemical used to make plastic has been identified as the new
primary suspect in a massive North American pet food recall. It was initially
thought that rat poison was the cause of the contamination.

However, it was still unclear how melamine, which is also used as a
fertilizer in Asia but banned for that purpose in the US, found its way into
wheat gluten used in the production process, said Menu Foods CEO Paul Henderson.
Nor was it clear why earlier tests identified the foreign agent as aminopterin, a
form of rat poison.

"We are angered that a source outside the company has
apparently adulterated the product, causing this regrettable loss," Henderson
said. He said the contamination was found in Chinese wheat gluten provided by a
new US supplier and has been discontinued since.